Y. Nishigaichi et al., DO METAL PERCHLORATES ACT AS A CONVENTIONAL LEWIS-ACID IN THE ALLYLSTANNATION OF ALDEHYDES, Journal of the Chemical Society. Perkin transactions. I, (11), 1993, pp. 1203-1204
Lithium, magnesium and calcium perchlorates are found to promote the a
ddition of allylic tin compounds to aldehydes via a six-membered cycli
c transition state, although not acting as a conventional Lewis acid l
ike BF3.